Method for imbedding a hollow needle in plastic material



R. W. OGLE April 3, 1956 METHOD FOR IMBEDDING A HOLLOW NEEDLE IN PLASTIC MATERIAL Filed July 9, 1951 F J1 @INVENTOR.

ATTORNEXS United States Patent 7 2,740,192 METHOD FOR IMBEDDING A HOLLOW NEEDLE IN PLASTIC MATERIAL Robert W. Ogle, Pasadena, Calif. Application July 9, 1951, Serial NO. 235,808 1 Claim. (Cl. 29-432) This invention relates to a method of imbedding a hollow needle into a plastic material.

In the attempt to manufacture cheap disposable syringes in which the body member is formed of a plastic mate rial such as polyethylene plastic, great difiiculty has been encountered in properly securing the needle in the plastic member. Various attempts at molding the needle in the plastic body have been made, and it has been discovered that the plastic, and particularly polyethylene plastic, on setting, will shrink from the needle and loosen therefrom, thereby breaking the seal and leaving the needle very loosely supported therein.

To avoid this, certain expediencies have been resorted to such as placing a kink in the needle, but these have not been altogether satisfactory. It has been discovered that if the needle is imbedded in the plastic in such a manner that none of the plastic material is removed so that when the needle is inserted, the needle is held under the elastic tension of the material itself, an excellent seal is formed and the needle is securely and safely held therein.

Accordingly, it is one object of this invention to provide an improved method of embodying a hollow needle in plastic material.

It is a further object of this invention to provide a method for embodying hollow needles in plastic material so that the needle is held under elastic tension by the material itself.

It is a further object of this invention to provide a method of inserting or imbedding a hollow needle in plastic material without removing any of the material.

These and other objects and advantages will be apparent from the annexed specification in which:

Figure l is a plan view of the fully assembled disposable syringe made in accordance with the present invention.

Figure 2 is an enlarged fragmentary plan view of the barrel of this syringe prior to inserting the needle.

Figure 3 is a view similar to Figure 2 showing the first step in the insertion of the needle.

Figure 4 is a view similar to Figure 3 showing a further step in the process.

Figure 5 is a view similar to Figure 4 showing one embodiment of the finished process.

Figure 6 is a similar view showing a second embodiment of the finished process.

Referring now more particularly to the drawings, there is shown a plastic syringe indicated generally by the numeral 10. This plastic syringe is of the type shown in my copending application Serial No. 235,807, filed July 9, 1951, now Patent No. 2,693,803, and includes a barrel section 11 which holds a plunger (not shown) and a hollow cork section 12. The barrel section 11 is provided with a post 13. The section 11 and post 13 are preferably formed of polyethylene plastic and it is necessary to pierce the post 13 and the upper end of the section 11 with the needle. This is done as follows:

The hollow needle is first bevelled at its lower end as shown at 14, and a mandrel size to permit it to be inserted within the hollow needle, as shown in Figures 3 and 4, having a sharpened end 16, is provided. This mandrel is mounted within the needle with a portion extending ahead of the needle as shown. The mandrel is then driven by any suitable means into the post 13, preferably axially thereof. As the sharpened mandrel is driven into the post, it forms a small opening in the post and forces the material surrounding this opening outwardly. It has been found that the mandrel during this action does not cut any of the material from the post but merely separates it. As the mandrel is driven further into the post, the needle itself enters the opening thus formed, and without cutting any material from the post is driven into the opening further separating the interior walls of the opening as shown in Figure 4. The mandrel is driven entirely through the wall of the section 11 as shown in Figure 4, and the needle may be driven to a position short of piercing through into the center of the section 11, as shown in Figure 5, or may also be driven fully through the section 11, as shown in Figure 6.

In either event, after the needle and mandrel have been driven in, the mandrel is then withdrawn, leaving the needle imbedded in the plastic material. If the needle is not to be driven completely through the plastic material, it is still unnecessary to cut a passage communicating with the needle. As shown in Figure 5, a passage 17 will remain as the polyethylene plastic has the ability to undergo a small amount of permanent set and the passage 17 will not entirely close on removal of the mandrel. This will, however, leave a shoulder 18 which further supports the needle.

When assembled in accordance with this method, the needle will be found to be securely and firmly imbedded in the plastic with the plastic material having been spread. This is possible because of the elastic nature of the material and consequently the needle is held in the material under elastic tension.

While there has been described the method of inserting the needle in the plastic in connection with the manufacture of the disposable syringe, it will be appreciated by those skilled in the art that the invention is not limited thereto, but is useful in any situation in which it is desired to imbed a small hollow tube in plastic material.

What is claimed is:

The method of affixing a hypodermic needle to an imperforate portion of a plastic needle hub molded integrally with a plastic syringe barrel which comprises the steps of: inserting a mandrel of a diameter sufiicient to prevent core formation telescopically through the bore of the needle, preliminarily forcibly thrusting a portion of said mandrel under the piloting influence of said needle into said hub to a predetermined extent, forcibly thrusting a portion of said needle in piloting relation over said mandrel into said hub to an extent substantially commensurate with that of the inward thrust of said mandrel whereby said portion of said needle is forthwith surroundingly seized and permanently secured within said hub solely under the radially inward compressive forces set up and acting within said hub, and withdrawing said mandrel from within said bore.

15, which will be of a References Cited in the file of this patent UNITED STATES PATENTS 

